Various types of airlift bioreactors are known. See for example, "Airlift Fermenters: Construction Behavior and Uses". Advances in Biotechnology Processes I, pages 67-95, 1983, Alan R. Liss, New York. N.Y.
A particular commercially available airlift bioreactor which can be readily modified according to the present invention has an upper growth chamber which is connected to a lower smaller diameter mixing chamber via a downwardly and inwardly sloping conical section. A gas mixture is sparged into the mixing chamber and sets up a gentle circulation of liquid growth medium within the growth chamber.
Certain cell lines are anchorage dependent as is well known in the art. This means that the cells must be grown in an environment wherein they can be attached to a solid support material. Heretofore, this has been accomplished, for example, by attaching the cells to stacked petrie dishes or by growing the cells in roller bottles. Each of these approaches has drawbacks such as the inability to achieve high volumetric cell density or inadequate circulation of nutrients, etc. necessary to growth of the cells.
Another known method of growing anchorage dependent cells uses gel bead immobilization. Using this technique, the cells are immobilized within small beads formed from alginate gel, for example. The cell containing beads may be suspended in a liquid growth medium and just like suspension type cells may be circulated to provide adequate contact with nutrients and dissolved gases to promote cell growth.